getUnknownRouteName method
Retrieves the unknown route name from your router.
Implementation
String getUnknownRouteName() {
  List<MapEntry<String, NyRouterRoute>> routes = NyNavigator
      .instance.router._routeUnknownMappings.entries
      .where((element) => element.value.getUnknownRoute() == true)
      .toList();
  if (routes.isNotEmpty) {
    return routes.first.value.name;
  }
  return "/";
}